Diode-Switched Level Shifter for Low Leakage and Timing Stability
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Solution Overview
Problem
Conventional level shifters suffer from poor timing characteristics and substantial leakage current, making them inadequate for reliable voltage transformation in electronic devices.
Innovation Solution
A low leakage level shifter design incorporating a series connection of diodes and switches, along with a capacitor, which reduces leakage current and improves timing characteristics by using transistors with shorted sources and gates, and additional capacitors for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional level shifters are used, then voltage transformation is achieved, but substantial leakage current occurs and timing characteristics are poor
Solution Approach 1:
The level shifter circuit is divided into multiple independent diode-switch units connected in series. Each unit consists of a diode and an associated switch that can be independently controlled. This segmentation allows the circuit to block leakage current paths while maintaining proper timing characteristics by enabling selective activation of different segments based on input voltage levels.
Solution Approach 2:
Capacitors are connected in parallel with each diode-switch unit to pre-charge and maintain voltage levels before the switching action occurs. This preliminary charging action ensures that when switches are activated, the desired voltage levels are already established, improving timing characteristics and reducing leakage current by preventing voltage fluctuations.
2Power
If conventional level shifters are used, then voltage level selection is achieved, but power consumption is high due to leakage current
Solution Approach 1:
The patent extracts and eliminates the leakage current paths that exist in conventional level shifters by introducing controlled switches in series with each diode. These switches are opened during non-conducting periods to completely block leakage current, while remaining closed during active periods to maintain proper voltage level shifting operation. This extraction of harmful leakage paths significantly reduces power consumption without affecting operational ease.
3Loss of energy
If additional diodes and switches are added, then leakage current is reduced, but device complexity increases
Solution Approach 1:
Each switch in the circuit serves multiple functions: it blocks leakage current during non-conducting states, enables voltage level shifting during active states, and works in conjunction with the parallel capacitor to maintain voltage stability. This multi-functionality reduces the need for separate dedicated components for each function, thereby limiting the increase in device complexity while achieving significant leakage current reduction.
Data Source
AI summary
A level shifter having: an input configured to receive an input signal, an output configured to provide an output signal, a voltage rail configured to provide a rail voltage, at least two diodes including a first and second diode connected in series between the voltage rail and the input, at least three switches, and a capacitor. The at least three switches include a first switch coupled between the voltage rail and the output of the first diode, a second switch coupled between the voltage rail and the output of the second diode, and a third switch coupled between the voltage rail and the input. The capacitor is coupled between the output of the second diode and ground.